JP2010246987A - Small vessel expandable stent and method for production of same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small vessel expandable stent and a method for producing the same. <P>SOLUTION: The partially expanded stent comprises a proximal end and a distal end in communication with one another, a tubular wall disposed between the proximal end and the distal end, the tubular wall having a longitudinal axis and a porous surface defined by a plurality of interconnecting struts. The partially expanded stent has been expanded ex vivo by the application of a radially outward force thereon from a first unexpanded position to a second pre-expanded position at which the stent has reached a point of plastic deformation. The partially expanded stent is further expandable in vivo upon the application of a radially outward force thereon from the second pre-expanded position to a third expanded position wherein the stent will undergo plastic deformation to reach a maximum yield point. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an expandable stent and a method for manufacturing the same. More particularly, the present invention relates to an expandable stent that is particularly suitable for placement in a small diameter body passage (eg, a lumen or artery having a diameter of about 3 mm or less).

  Stents are generally known. Indeed, the term “stent” is used interchangeably with terms such as “intraluminal tube graft” and “expandable prosthesis”. As used throughout this specification, the term “stent” is intended to have a broad meaning, and any expandable for implantation within a body passageway (eg, a lumen or an artery) It also contains various prostheses.

  In the last decade, the use of stents has led to an increased amount of attention that should naturally be given to the potential of these devices to be used as an alternative to surgery in some cases. In general, stents are used to obtain and maintain the patency of the passage while maintaining the integrity of the body passage. As used herein, the term “body passage” is intended to have a broad meaning and encompasses any conduit (eg, natural or iatrogenic) within the human body, , Organs selected from the group consisting of respiratory conduits, gastrointestinal conduits, and the like.

  Stent development (development) is targeted so that almost all currently available stents are only applied with sufficient force to maintain the patency of this body passage during stent expansion. It has evolved to a stage that relies on controlled plastic deformation of the overall structure of the stent in the body passageway.

  Generally, in many of these systems, the stent is delivered to the target area of the body passage by the catheter system in relation to the balloon. When the stent is properly positioned (eg, for endovascular implantation, the target area of the blood vessel can be filled with contrast agent to facilitate visualization during fluoroscopy), the balloon is inflated. Thereby plastically deforming the entire structure of the stent so that the latter is in proper condition with respect to the body passageway. As noted above, the amount of force applied is at least as long as necessary to expand the stent while maintaining the patency of the body passage (i.e., the applied force reduces it). Exceeding the minimum force that would cause the stent material to undergo plastic deformation). At this point, the balloon is deflated and retracted from within the catheter and subsequently removed. Ideally, the stent will remain in this position, maintaining the target area of the body passageway substantially unoccluded (or narrowed).

For example, for a discussion of previous stent design and deployment systems listed below, reference is made to some of the patents, the contents of each of which are incorporated herein by reference. That is,
United States Patent No. 4,733,665 (Palmaz),
United States Patent No. 4,739,762 (Palmaz),
United States Patent No. 4,800,882 (Gianturco),
United States Patent No. 4,907,336 (Gianturco),
US Pat. No. 5,035,706 (Gianturco et al.),
United States Patent 5,037,392 (Hillstead),
United States Patent 5,041,126 (Gianturco),
United States Patent No. 5,102,417 (Palmaz),
United States Patent No. 5,147,385 (Beck et al.),
US Pat. No. 5,282,824 (Gianturco),
United States Patent No. 5,316,023 (Palmaz et al.),
Canadian Patent 1,239,755 (Wallsten),
Canadian Patent 1,245,527 (Gianturco et al.),
Canadian Patent Application No. 2,134,997 (Penn et al.),
Canadian Patent Application No. 2,171,047 (Penn et al.),
Canadian Patent Application No. 2,175,722 (Penn et al.),
Canadian Patent Application No. 2,185,740 (Penn et al.),
Canadian Patent Application No. 2,192,520 (Penn et al.),
International Patent Application No. PCT / CA97 / 00151 (Penn et al.),
International Patent Application No. PCT / CA97 / 00152 (Penn et al.), And
International Patent Application No. PCT / CA97 / 00294 (Penn et al.).

  Published International Patent Application No. WO 95/26695 [Lau et al. (Lau)] teaches a self-expandable, foldable stent that would probably be delivered using a catheter or other technique. . The point of novelty in Lau is a stent that can be folded along its longitudinal axis. The folding is accomplished by applying bending and torsional stresses to the stent, and the stress is greater than the material used to manufacture the stent, causing plastic deformation of the stent. The minimum stress is not exceeded, i.e., the application of these stresses to the stent results in the accumulation of mechanical energy within the stent, but does not result in the occurrence of any plastic deformation.

  US Pat. No. 5,643,312 [Fischell et al. (Fischell)] teaches a stent having a number of closed circular structures connected by a series of longitudinal members. The stent is initially manufactured in a pre-arranged form with ellipses connected by longitudinal members (see FIGS. 4 and 5). The stent in the pre-arranged form, rather, is obtained by translating a balloon stent delivery catheter and a pair of opposing longitudinal members firmly securing the ellipse at each end of the structure. Is arranged at the end of an elliptical arc folded around the short axis (see FIG. 6).

  Many conventional stents rely on plastic deformation of the material from the stent configured as a suitable arrangement. The stress-strain profile substantially corresponds to the given material (eg, stainless steel) from which the stent is constructed. This profile has two unique and interesting areas.

  The first region is the portion of the profile where the material exhibits an elastic behavior. In particular, this profile is substantially straight (ie, substantially constant slope). During this first region, if the expanding force is removed, the stent will return close to its original diameter, i.e., the material will still undergo stent contraction if the force is removed. It is in an elastic state that comes down.

  The second region of the profile is reached when the occurrence of shrinkage is substantially reduced, i.e., the stent is less than 15%, preferably less than 10%, more preferably less than the expanded diameter of the stent. Return less than 5%. In effect, this is the elastic limit of the material. Once this point is reached, the material begins to exhibit plastic behavior. The second region of this profile has three consecutive interesting sub-regions along this profile: (i) plastic deformation or softening, (ii) strain hardening, and (iii) necking.

  Once the material begins to exhibit plastic behavior, the continued expansion force causes the material to permanently deform, resulting in collapse. This is known as “plastic deformation” or “yield”. In this sub-region, the stent will continue to expand without substantially increasing the expansion force. When the term “maximum tolerance point” is used in the context of an expanded stent throughout this specification, it is further expanded to expand the stent resulting in a reduction in the cross-sectional area of the further expanding material. It is intended to mean a point on the profile where a force can be applied to the stent. In other words, above this “maximum tolerance point”, the beginning of the “strain hardening” subregion of the profile occurs, where the profile rises as a continuous curve to the maximum stress, also known as “extreme stress”. To do. Exceeding the ultimate stress leads to the beginning of the “necking” sub-region of the profile, where the cross-sectional area of the stent material is reduced in the local region of the stent. Since this cross-sectional area is reduced, the smaller area can only carry a reduced load resulting in a descending curve from the ultimate stress until the material breaks at "fracture stress".

  Thus, in conventional stents that rely on plastic deformation for deployment, the unexpanded stent is typically in an elastic state (ie, the first region of the profile described above) and is The state is expanded to the point (ie the second region of the profile described above), in particular to the point leading to the latter first sub-region. In practice, it is generally desirable to deploy the stent to a diameter that is as close as possible to the maximum allowable point discussed above and never exceeded. The reason is that the radial stiffness of the stent is maximized.

  One application of a stent that receives little or no attention is a small diameter body passage stent. As used throughout this specification, the term “small diameter body passage” is intended to mean an artery or lumen having a diameter of 3 mm or less (less than or equal to 3 mm). As used throughout this specification, the term “large diameter body passage” is intended to mean an artery or lumen having a diameter greater than 3 mm.

  One likely reason for this is that conventional stents are designed for implantation into large diameter body passages. More specifically, a stent that relies on controlled plastic deformation of the overall structure of the stent in the targeted body passage is designed to have a maximum allowable point at an enlarged diameter equal to a larger diameter body passage. For most conventional such stents, the maximum allowable point is reached when the expanded stent diameter is about 4 mm to about 5 mm. In the unexpanded state, the diameter of the stent is about 1.5 mm. Such stents are not suitable for implantation into small body passageways, ie, arteries or lumens having a diameter of about 3 mm or less. The main reason for this is that if it is expanded to a diameter of about 3 mm or less, i.e. well below the maximum allowable point, the relatively high resilience inherent in such body passages. And the poor radial stiffness of the stent.

  It would therefore be desirable to have an improved stent that overcomes these disadvantages. It would be further desirable if the improved stent could be easily manufactured. It would be further desirable if the improved stent could be deployed using a conventional stent delivery system.

  It is an object of the present invention to provide a new expandable stent that eliminates or reduces at least one of the above-mentioned disadvantages of the prior art.

  Accordingly, in one of its aspects, the present invention provides a proximal end and a distal end in communication with each other, a tubular wall disposed between the proximal and distal ends, the tubular wall having a longitudinal axis. An unexpanded stent having a porous surface defined by a plurality of interconnecting struts, wherein the stent has a maximum tolerance when the tubular wall has a diameter of about 3.5 mm or less. An unexpanded stent is provided that can be expanded by applying a radially outward force thereto to undergo plastic deformation to the point.

In another aspect, the present invention comprises a proximal end and a distal end in communication with each other, a tubular wall disposed between the proximal and distal ends, the tubular wall having a longitudinal axis and An unexpanded stent having a porous surface defined by a plurality of interconnecting struts, wherein the stent is from a first position that has not been expanded by application of a radially outward force thereto. To a pre-expanded second position where the stent reaches a plastic deformation point; and
From the pre-expanded second position to an expanded third position that will undergo plastic deformation to a maximum allowable point when the tubular wall has a diameter of about 3.5 mm or less, An unexpanded stent is provided that is expandable.

In another aspect, the present invention comprises a proximal end and a distal end in communication with each other, a tubular wall disposed between the proximal and distal ends, the tubular wall having a longitudinal axis and A partially expandable stent having a porous surface defined by a plurality of interconnecting struts,
By applying a radially outward force thereto, the stent is expanded from a first unexpanded position to a pre-expanded second position where the stent reaches a plastic deformation point; and
By applying a radially outward force thereto, the pre-expanded second position can be further expanded to an expanded third position that will undergo plastic deformation to the maximum allowable point. A stent is provided. Desirably (but not necessarily), in the expanded third position of the stent, a maximum allowable point is reached when the tubular wall has a diameter of about 3.5 mm or less.

In yet another aspect, the present invention provides:
A catheter;
An expandable member disposed on an outer periphery of the catheter;
A partially enlarged stent disposed on an outer periphery of the catheter, the stent including a proximal end and a distal end communicating with each other, and a tubular wall disposed between the proximal end and the distal end; The tubular wall has a longitudinal axis and a porous surface defined by a plurality of interconnecting struts, the stent delivery kit comprising:
The stent is
By applying a radially outward force thereto, the stent is expanded from a first unexpanded position to a pre-expanded second position where the stent reaches a plastic deformation point; and
By applying a radially outward force thereto, the pre-expanded second position can be expanded to an expanded third position that will undergo plastic deformation to the maximum allowable point. Providing a stent delivery kit. Desirably (but not necessarily), in the expanded third position of the stent, a maximum allowable point is reached when the tubular wall has a diameter of about 3.5 mm or less.

In yet another aspect, the present invention provides a method of attaching an unexpanded stent to the outer periphery of a catheter having an expandable member disposed thereon, wherein the unexpanded stent is in proximal communication with each other. And a distal end, comprising a tubular wall disposed between the proximal and distal ends, the tubular wall having a longitudinal axis and a porous surface defined by a plurality of interconnecting struts; The stent can be expanded by applying a radially outward force thereto, wherein
(I) expanding the unexpanded stent to a pre-expanded second position where the stent reaches a plastic deformation point to produce a partially expanded stent; and
(Ii) providing a method of placing the partially expanded stent on the expandable member of the catheter;

  Accordingly, the present inventors have developed a novel stent that is fundamentally different from previously produced stents. In particular, conventional stents are single from the initial unexpanded state in which the stent material exhibits an elastic behavior to the fully (ie, final) expanded state in which the stent exhibits a plastic behavior. The approach in the preferred embodiment of the present invention is based on the delivery of a pre-expanded stent to the plastic deformation stage prior to placement in the subject. ing. Thus, the preferred embodiment of the stent is deployed using two separate expansion steps. In this preferred embodiment, the final expansion step is performed in vivo, as will be developed below, whereas the initial expansion step is performed ex vivo.

While there are many benefits arising from this stent, the three main benefits are:
(I) Volume reduction of the stent, i.e., because the stent is placed in vivo from a pre-expanded state, it is not expanded when compared to an unexpanded stent placed in vivo Less material is required to manufacture the stent, i.e. the stent may be composed of small tubes,
(Ii) the amount of material needed to construct the stent is reduced, so that the flexibility of the stent is improved and / or
(Iii) The ability to provide a stent with a maximum tolerance point that reaches a diameter equal to the typical diameter of a small body passage (ie, related to the prior art).

  While the present stent is suitable for use with both large and small body passages, it is particularly suitable for the latter. From a practical point of view, much of the state of the art in stents (stenting) uses a low profile balloon attached to a catheter. Conventionally, the balloon can have a diameter from about 1.0 mm to about 1.3 mm. Most conventional stents have a ratio of final expanded diameter to unexpanded diameter of about 3.0 (this has reached the stage of plastic deformation and the stent material is Conventional stents have a final expanded diameter of 4.5 to 5.0 mm for use in small diameter body passages, ensuring that stress is applied to the vicinity of the maximum allowable point). Make it inappropriate.

  The novel application of the stent is that once the stent is about 3.5 mm or less, desirably about 3.3 mm, more desirably within the range of about 2.2 mm to about 3.3 mm, most desirably about 2.5 mm to about 3.3 mm. When expanded to a diameter in the range of 3.0 mm, the ratio of optimal expanded diameter to unexpanded diameter is small enough so that the stent material can be matched with the desire to reach the maximum allowable point It is to produce an unexpanded stent with a diameter. In practice, this is designed to expand the stent to allow it to be initially mounted on a delivery system, eg, a low profile balloon placed on the periphery of a conventional catheter. Has been achieved by doing. Once so attached, the stent is delivered to a targeted small diameter body passage where a second and separate expansion step is then enabled to place the stent. Thus, as described above, in the preferred embodiment of the stent, the initial expansion process is processed ex vivo and the final expansion process is processed in vivo.

  According to our knowledge, this is an approach to the initial goal for a small diameter body passage stent (stenting).

FIG. 1 is a schematic view of one embodiment for manufacturing the stent in its unexpanded state. FIG. 2 is a perspective view schematically illustrating one embodiment that enables partial expansion of an unexpanded stent. FIG. 3 is a cross-sectional view schematically illustrating one embodiment that enables partial expansion of an unexpanded stent. FIG. 4 is a schematic diagram showing another embodiment in which partial expansion of an unexpanded stent is effective. FIG. 5 is a schematic diagram showing another embodiment in which partial expansion of an unexpanded stent is effective. FIG. 6 is a diagram showing an outline of attachment of the partially expanded stent manufactured in FIGS. 2 to 5 to the outer periphery of the balloon attachment catheter. FIG. 7 is a diagram showing an outline of attachment of the partially expanded stent manufactured in FIGS. 2 to 5 to the outer periphery of the balloon attachment catheter. FIG. 8 shows the placement of a balloon-attached catheter having a partially expanded stent therein into a small diameter body passage. FIG. 9 illustrates the final expansion of a partially expanded stent within a small diameter body passage.

  The inherent design of the porous surface is not particularly limited. Desirably, in an unexpanded state, at least two of the struts meet to define an acute angle at the intersection.

  In the context of the present stent, various repeating patterns on the porous surface of the tubular wall are particularly advantageous. Generally, a desirable repeating pattern is a polygon having a pair of sidewalls substantially parallel to the longitudinal axis, a concave first wall having a first apex, and a convex first having a second apex. The first wall portion and the second wall portion are a plurality of cross members arranged so as to define a first repeating pattern connecting the side walls. Desirably, at least one of the first top and the second top, more desirably both, are substantially flat. The first top and the second top may be of the same or different length.

  Preferably, the sidewall comprises longitudinal struts disposed substantially parallel to the longitudinal axis of the stent, each longitudinal strut having a longitudinal strut diameter on the bend of the stent. And a pair of substantially complementary bending and expanding means for expansion and compression. In practice, the bending means may comprise at least one lateral portion located within each longitudinal strut. The lateral portion may have a pointed top, a rounded top, a flat top, and the like. Furthermore, the bending means may comprise one or more such transverse portions per longitudinal strut. If two parts are provided per longitudinal post, they may be symmetric or asymmetric. Further, the two parts may have substantially the same shape and different sizes, or they may have different shapes and sizes, or they are substantially the same. May have different shapes and sizes.

  A preferred bending means comprises an S-shaped portion, for example, a pair of coupled curved portions, each curved portion having an arc of about 180 ° or more. The curved portions may be substantially the same or different sizes.

Non-limiting examples of various desirable repeating patterns that incorporate some or all of these features and that are useful in the context of the present stent are disclosed in the following co-pending patent applications, the contents of each of which are , Incorporated herein by reference. That is,
Canadian Patent Application No. 2,134,997 (Penn et al.),
Canadian Patent Application No. 2,171,047 (Penn et al.),
Canadian Patent Application No. 2,175,722 (Penn et al.),
Canadian Patent Application No. 2,185,740 (Penn et al.),
Canadian Patent Application No. 2,192,520 (Penn et al.),
International Patent Application No. PCT / CA97 / 00151 (Penn et al.), And
International Patent Application No. PCT / CA97 / 00152 (Penn et al.).

  Of course, many conventional repeating patterns may be incorporated into the stent.

  The stent may be composed of a number of suitable initial materials. Desirably, the initial material is a thin tube of metal or alloy. In one desirable embodiment, the initial material may be plastically deformable, and non-limiting examples of such materials include stainless steel, titanium, tantalum, and the like. In other desirable embodiments, the initial material may be one that expands through a temperature dependent memory (ie, a material that will expand when a certain temperature is reached). Limited examples include balloon expandable nitinol (shape memory alloy) and the like.

  Referring to FIG. 1, a side elevational view of a solid tube 10 of initial material for manufacturing the present stent is illustrated. The nature of the solid tube 10 is not particularly limited and includes all materials conventionally used to manufacture stents. In one desirable embodiment, the solid tube 10 is made of a plastically deformable material. As discussed above, a non-limiting example of such a material is stainless steel. In other desirable embodiments, the solid tube 10 is constructed of a material that will expand when a certain temperature is reached. In this embodiment, the material may be a self-expanding metal alloy (eg, nitinol) at a temperature of at least about 30 ° C., desirably in the range of about 30 ° C. to about 40 ° C. Desirably, the solid tube 10 has a thickness in the range of about 0.003 inches to about 0.015 inches.

  If the stent is to be used in a small body passageway, it is desirable for the solid tube 10 to have a diameter in the range of about 0.5 mm to about 1.0 mm. If the stent is to be used in a large body passage, the solid tube 10 has a diameter greater than about 1.0 mm, preferably in the range of about 1.3 mm to about 1.6 mm. It is desirable to have.

The solid tube 10 is then subjected to a process that results in this portion being removed to define a porous surface. The exact nature of this process is not particularly limited, but is preferably processed by being enabled on a computer programmable laser cutting system, schematically illustrated at 20. The laser cutting system 20
(I) receiving the solid tube 10;
(Ii) moving the solid tube 10 longitudinally and rotated to selectively remove portions of the solid tube 10 under a laser beam, thereby defining a porous surface; and
(Iii) Operating by cutting the desired length of the stent portion of the solid tube 10.

  A suitable such laser cutting system is known in the art as the LPLS-100 series stent cutting machine. The operation of this system to produce an unexpanded stent is within the understanding of those skilled in the art.

  Thus, the stent produced by the laser cutting system 20 is in an unexpanded state, i.e., the stent will exhibit an elastic behavior in this state.

  If desired, the stent may be subjected to further processing to apply a coating material thereon. The coating material may be disposed continuously or discontinuously on the surface of the stent. Further, the coating may be placed on the inner and / or outer surface of the stent. The coating material provides a biologically inert material (eg, reduces stent thrombogenicity), a pharmaceutical composition that is leached into the wall of the body passage after implantation (eg, provides an anticoagulant effect) , Delivering a drug to the body passageway, and the like), a radioactive composition (which makes the stent radiopaque during delivery), and the like.

  The stent is desirably coated with a biocompatible coating to minimize adverse interactions with the walls of the body vessel and / or the fluid, usually blood, flowing through the tube. The coating is desirably a polymeric material, which is typically supplied by applying a pre-formed polymer spray in solution or solvent to the stent and removing the solvent. Non-polymeric coating materials may alternatively be used. A suitable coating material, such as a polymer, may be polytetrafluoroethylene or silicone rubber or a polyurethane known to be biocompatible. Desirably, however, the polymer has zwitterionic attachment groups, usually ester ammonium phosphate groups, such as choline phosphoryl groups or the like. Examples of suitable polymers are described in published international applications WO-A-93 / 16479 and WO-A-93 / 15775. The polymers described in those specifications are hemo-compatible, usually biocompatible, and additionally lubricious. When biocompatible coatings are used, ensure that the stent surface is fully coated to minimize adverse interactions, such as with blood, which may lead to thrombosis That is important.

  This good coating can be achieved by appropriate selection of coating conditions, such as the viscosity of the coating solution, the coating technique and / or the solvent removal step. The coating, if present, can be applied in a pre-expanded or contracted state. Desirably, the stent is preliminarily designed to eliminate or mitigate potential obstacles to the coating during the transition from the contracted (ie, unexpanded) state to the pre-expanded state. It is subjected to coating in an expanded state.

  With reference to FIGS. 2 and 3, one preferred embodiment is illustrated schematically which will effect partial expansion of the unexpanded stent produced in FIG. 1. In particular, there is shown a solid mandrel 50 having a tapered tip 55 and an unexpanded stent 30 manufactured by the laser cutting system 20 (FIG. 1). The tapered tip 55 of the mandrel 50 is located at one open end of the unexpanded stent 30. Thereafter, the mandrel 50 is pushed into the stent 30 in the direction of arrow A. In practice, this is accomplished by holding the mandrel 50 stationary and pressing the stent 30 onto the mandrel 50, or holding the stent 30 stationary and pushing the mandrel 50 into the stent 30. obtain. Referring to FIG. 3, when the mandrel 50 enters the stent 30, the tapered tip 55 is sufficiently large on the stent 30 in the direction of arrow B so that the stent reaches the stage of plastic deformation. A radially outward force is applied to the part or when the mandrel 50 is removed, the partially expanded stent is less than 15%, preferably less than 10% of the expanded diameter of the stent, More desirably, it will shrink back by less than 5%. The partially expanded stent is shown as 30a.

  Referring to FIGS. 4 and 5, there is schematically illustrated one preferred embodiment that works for partial expansion of the unexpanded stent manufactured in FIG. In particular, there is shown an expandable mandrel 60 having a tapered tip (tip) 65 and a series of expandable vanes 70. The diameter of the expandable mandrel 60 (in the unexpanded state) is smaller than that of the unexpanded stent 30. Accordingly, the expandable mandrel 60 can be easily placed with the stent 30 as illustrated in FIG. Once the expandable mandrel 60 is placed within the stent 30 (desirably, both ends of the expandable mandrel 60 protrude from both ends of the stent 30), the interior of the expandable mandrel is pressurized (eg, The diameter of the expandable mandrel 60 or similar means in the direction of arrow C on the sufficiently large stent 30 so that the stent reaches the plastic deformation stage as a result. A stent that is partially expanded when an outward force is applied, i.e., when the mandrel 60 is removed, is less than 15% of the expanded diameter of the stent, desirably less than 10%, more desirably. Shrinks by less than 5%. A partially expanded stent is shown as 30a. After partial expansion of the stent 30, the expandable mandrel 60 is retracted and removed from the partially expanded stent 30a. If the stent is to be used in a small body passage, the diameter of the partially expanded stent is at least about 1.3 mm, desirably in the range of about 1.4 mm to about 1.6 mm, or It is desirable that the diameter be sufficient to be placed on the expandable member of the catheter delivery system.

  Referring to FIGS. 6 and 7, there is a schematic of the attachment of a partially expanded stent balloon manufactured in FIGS. 2-5 (or by some other means) to a catheter 100 loaded with a balloon. Is illustrated. Catheter 100 includes a balloon 110 attached to its distal end. Balloon 110 is in communication with tube 115. Guide wire 105 is coaxially disposed within balloon 110 and tube 115. Catheter 100 is conventional and is probably a low profile balloon as discussed above, for example. Balloon 110 is placed within partially expanded stent 30a and crimps (eg, mechanically) balloon 110 in the direction of arrow D (FIG. 7). Such attachment of the stent to the balloon is conventional.

  The placement of the partially expanded stent 30a will be described with reference to FIGS. FIG. 8 illustrates the placement in a small diameter body passageway of a catheter loaded with a balloon having a partially expanded stent attached thereto. FIG. 9 illustrates the final expansion of a partially expanded stent within a small diameter body passage.

  Thus, there is illustrated a small body passageway 120 having a stenosis 125 therein. A catheter 100 having a partially expanded stent 30a attached thereto is steered to stenosis in a conventional manner. Within the appropriate location, the balloon 110 is pressurized (eg, by pushing fluid into the balloon 100 via the tube 115), resulting in a radially outward on the partially expanded stent 30a. This causes the application of force. The exercise of this force results in further plastic deformation of the partially expanded stent 30a until it reaches a fully expanded state 30b in which the stenosis 125 is relieved, and in this fully expanded state The stent material approaches the maximum allowable point but does not exceed it.

  As will be apparent to those skilled in the art, ensure that the maximum tolerance point is not exceeded during expansion of the partially expanded stent 30a to the fully expanded state 30b. That is important. This is because it can cause catastrophic failure of the stent. In other words, the expansion of the stent should not be a stress-strain region beyond the first sub-region of the second region of the profile discussed above. In the present specification under consideration, one skilled in the art could readily adjust the following facts to produce a useful stent. (I) the particular porous design of the stent, (ii) the material used to manufacture the stent, (iii) the diameter of the tubular material from which the unexpanded stent is made, (iv) the stress reaching the plastic deformation point The strain level, and (v) the stress-strain level reaching the maximum allowable point.

  While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limited sense. Various modifications of the illustrated embodiment, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon review of this description. Therefore, it is expected that the appended claims will cover any such modifications or embodiments.

  DESCRIPTION OF SYMBOLS 10 ... Solid tube, 20 ... Laser cutting system, 30 ... Stent, 50 ... Mandrel, 55 ... Tip, 60 ... Mandrel, 65 ... Tip, 70 ... Bain, 100 ... Catheter, 105 ... Guide wire, 110 ... Balloon, 115 ... Tube, 120 ... body passage, 125 ... stenosis.

Claims (31)

  A proximal end and a distal end in communication with each other, and a tubular wall disposed between the proximal and distal ends, the tubular wall by a longitudinal axis and a plurality of interconnecting struts An unexpanded stent having a defined porous surface, the stent being subjected to plastic deformation to a maximum allowable point when the tubular wall has a diameter of about 3.5 mm or less, An unexpanded stent that can be expanded by applying a radially outward force thereto. The stent is
From a first unexpanded position to a pre-expanded second position where the stent reaches a plastic deformation point; and
From the pre-expanded second position to an expanded third position that will undergo plastic deformation to a maximum allowable point when the tubular wall has a diameter of about 3.5 mm or less, The unexpanded stent of claim 1, which is expandable.   The unexpanded stent of claim 2, wherein in the pre-expanded second position, the stent has a diameter greater than about 1.1 mm.   4. The expansion according to claim 2 or 3, wherein in the pre-expanded second position, the stent has a sufficiently large diameter to receive expansion means for further expanding the stent in the stent. Not a stent.   5. An unexpanded stent according to any one of claims 2 to 4, wherein in the first unexpanded position, the stent has a diameter of about 1.1 mm or less.   5. The unexpanded stent according to any one of claims 2 to 4, wherein in the first unexpanded position, the stent has a diameter in the range of about 0.5 mm to about 1.1 mm. .   5. The unexpanded stent according to any one of claims 2 to 4, wherein in the first unexpanded position, the stent has a diameter in the range of about 0.5 mm to about 1.0 mm. .   8. An unexpanded stent according to any one of the preceding claims, wherein the tubular wall has a substantially circular cross section.   The unexpanded stent according to any one of claims 1 to 8, wherein the tubular wall portion is made of a plastically deformable material. A proximal end and a distal end in communication with each other, and a tubular wall disposed between the proximal and distal ends, the tubular wall defined by a longitudinal axis and a plurality of interconnecting struts A non-expanded stent having a defined porous surface, wherein the stent has a plastic deformation point from a first position that has not been expanded by application of a radially outward force thereto. To a pre-expanded second position to reach and
From the pre-expanded second position to an expanded third position that will undergo plastic deformation to a maximum allowable point when the tubular wall has a diameter of about 3.5 mm or less, An unexpanded stent that is expandable.   11. The unexpanded stent of claim 10, wherein in the pre-expanded second position, the stent has a diameter greater than about 1.1 mm.   12. The expansion according to claim 10 or 11, wherein in the pre-expanded second position, the stent has a sufficiently large diameter to receive expansion means for further expanding the stent in the stent. Not a stent.   13. The unexpanded stent according to any one of claims 10 to 12, wherein in the first unexpanded position, the stent has a diameter of about 1.1 mm or less.   The unexpanded stent according to any one of claims 10 to 12, wherein in the first unexpanded position, the stent has a diameter in the range of about 0.5 mm to about 1.1 mm. .   13. The unexpanded stent according to any one of claims 10 to 12, wherein in the first unexpanded position, the stent has a diameter in the range of about 0.5 mm to about 1.0 mm. .   16. An unexpanded stent according to any one of claims 10 to 15, wherein the tubular wall has a substantially circular cross section.   The unexpanded stent according to any one of claims 10 to 16, wherein the tubular wall portion is made of a plastically deformable material. A proximal end and a distal end in communication with each other, and a tubular wall disposed between the proximal and distal ends, the tubular wall by a longitudinal axis and a plurality of interconnecting struts A partially expandable stent having a defined porous surface,
By applying a radially outward force thereto, the stent is expanded from a first unexpanded position to a pre-expanded second position where the stent reaches a plastic deformation point, and the diameter there A stent that is further expandable from the pre-expanded second position to an expanded third position that will undergo plastic deformation to a maximum allowable point by application of a force outward in the direction.   19. The partially expanded stent of claim 18, wherein in the expanded third position of the stent, the tubular wall reaches a maximum allowable point when having a diameter of about 3.5 mm or less. A catheter;
An expandable member disposed on an outer periphery of the catheter;
A partially expanded stent disposed on the outer periphery of the catheter, the stent comprising a proximal end and a distal end communicating with each other, and a tubular wall disposed between the proximal end and the distal end. The tubular wall has a longitudinal axis and a porous surface defined by a plurality of interconnecting struts, the stent delivery kit comprising:
The stent is
By applying a radially outward force thereto, the stent is expanded from a first unexpanded position to a pre-expanded second position where the stent reaches a plastic deformation point, and the diameter there A stent delivery kit that can be expanded from the pre-expanded second position to an expanded third position that will undergo plastic deformation to the maximum allowable point by application of a force outward in the direction. .   21. The stent delivery kit of claim 20, wherein in the expanded third position of the stent, the tubular wall reaches a maximum allowable point when having a diameter of about 3.5 mm or less.   The stent delivery kit according to any one of claims 20 to 21, wherein the stent is mechanically mounted to the expandable member.   24. The stent delivery kit of claim 22, wherein the stent is deformed on the expandable member. A method of attaching an unexpanded stent to the outer periphery of a catheter having an expandable member disposed therein, the unexpanded stent comprising a proximal end and a distal end communicating with each other, the proximal end and the distal end A tubular wall portion disposed between and having a longitudinal axis and a porous surface defined by a plurality of interconnecting struts, the stent being directed radially outward thereto A method that is expandable by application of force,
(I) expanding the unexpanded stent to a pre-expanded second position where the stent reaches a plastic deformation point to produce a partially expanded stent; and (ii) of the catheter Placing the partially expanded stent on the expandable member.   25. The method of claim 24, wherein step (i) comprises propelling the stent over a mandrel in a direction substantially parallel to the longitudinal axis.   25. The method of claim 24, wherein step (i) comprises pressing the stent over a mandrel in a direction substantially parallel to the longitudinal axis.   25. The method of claim 24, wherein step (i) comprises pulling the stent over a mandrel in a direction substantially parallel to the longitudinal axis.   28. A method according to claim 26 or 27, wherein the mandrel is tapered.   25. The method of claim 24, wherein step (i) comprises propelling the stent over a die in a direction substantially parallel to the longitudinal axis.   25. The method of claim 24, wherein step (i) comprises placing the stent on the expandable means and subsequently expanding the stent to the pre-expanded second position. .   31. A method according to any one of claims 24 to 30, wherein step (ii) comprises deforming the partially expanded stent on the expandable member of the catheter.

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